Testing your meter before using it on equipment is paramount, as bartamos stated. You need to know your equipment is working properly. He also covered using resistance or ohms function vs. Continuity ( sometimes denoted by a diode setting ), also important to know which is being used.
In the ohms or resistance setting a properly calibrated meter should read zero ohms with the test leads connected, or else it isn't worth using to actually measure resistance. On analog meters there was a knob to turn, on better digital meters there is a calibrate button.
If the meter being discussed is calibrated and being used in its resistance setting, then 300 ohms is not enough. As stated by waltervogel it will still have current flow. The reading should be infinite or Megaohms range depending on the meter.
